A NEW SPECIES OF MONOCHAETIA. (With Plate VIII.)

By Malcolllz Wilso~z, D.Sc., F.R.S.E., F.L.S. Render in Mycology, U~~iversity of Edinburgh

ntzd 1;. C . Fovd-Kobcrtso~z, B.Sc.

Ilzdian 1;ovest Sevvicc. The fungus forming the subject of this note was found on the

dead leaves of Cry$tomeria japo~zica D. Don, which were still attached to the cast shoots. I t was collected in November, 1921, a t Raith, Fife, on shoots which had evidently lain on the ground for some months. Detailed investigation of the material was not commenced until January, 1923.

The fructifications, which are isolated and found sparingly on all sides of the leaf, arc dull black and smooth, in shape oval to elliptical and up to I ; -75 mm. in size when mature. They may project as much as -3 mm. above the surface of the leaf; young fructifications are more rounded and project to a less degree. On examination the mature fructification appears to consist almost entirely of a spherical mass of dark-coloured spores and is encircled by the ruptured epidermis, an indication that it was in the early stages embedded in the tissue of the leaf. Sections confirm this, and the fructification, seen just below the epidermis, is globose, consisting of a reddish-brown wall about 20p in thickness, made up of interwoven hyphae, which on the outer surface gradually pass off into the tissue of the leaf (fig. I). The inner surface of the wall is sharply delimited by the hyaline sporophores which project from it thickly and bear the elongated spores. As developmcnt proceeds the epidermis and wall of the fructification immediately below it rupture and the free edges of both form an aperture which gradually widens to expose the spore-bearing layer. The fructification, immediately after dehiscence, is flask-shaped and, in consequence, the sporo- phores near the opening are still directed inwards (fig. 2). As the aperture widens this appearance is lost, the spore-bearing layer becoming finally almost flat. Mucilage is evidently pro- duced, even before rupture, by degeneration of the wall and sporophores, and dehiscence is probably brought about by absorption of water and consequent swelling. The mucilage flows out over the surface as a cushion-like layer and carries out the spores embedded in i t ; by the time that the fructification is widely open the majority of the spores are found on the surface of the leaf in the dark-coloured mass previously referred to.

190 Transactiofzs British Mycological Society. The spores (fig. 3) are spindle-shaped, constantly five-celled, slightly constricted at the septa, the three central cells (b, c, d) with smooth, chocolate-brown walls of even thickness and pale yellow granular contents; the central cell (c) is invariably the darkest. The terminal cells (a, e) are hyaline, occasionally sub- hyaline, with scanty colourless contents and often with a single, rather large oil drop. The proximal cell ( a ) , which possesses a wall of marked thickness, is separated from the sporophore by a cross wall; the sporophore itself is hyaline, 4-zop long, 1-2 p thick and is often divided into two or three cells. The distal cell (e) is hyaline, thin-walled, with scanty contents, occasion- ally with an oil drop and is prolonged into a tapering seta which is generally bent or curved, 20-3zp long and barely xp thick a t the base. The process of spore development has not been elucidated but the structures shown at f and g in fig. 3 appear to be early stages.

The mycelium in the leaf consists of very delicate hyaline hyphae which spread in all directions through the tissues. At maturity the fructifications appear very shrunken and are not easily distinguished in the dead leaf. Although at the time of examination the material had been kept for fourteen months in a dry condition in the laboratory, the spores released from the soaked material were found in a germinating condition. Ger- mination, which may take place within twenty-four hours, is invariably preceded by a change in colour and cell contents. The brown cells, which alone produce germ tubes, become paler in colour and conspicuous oil drops appear in the contents, although they are rarely or never seen in the resting spore.

On germination the outer layer of the wall is ruptured and the inner colourless layer emerges to form a germ tube of variable thickness usually about 2 p in diameter (fig. 4). Near the point of emergence the protoplasm becomes paler in colour and in the germ tube is completely hyaline ; the oil drops generally flow out as development proceeds. Whilst still very short the germ tube may bifurcate before any cross septa are formed (a , fig. 4).

In most cases germ tubes are only produced from the dark- coloured cells adjoining the central one, each of which may produce two. Most frequently two germ tubes are produced from the whole spore, each of the cells contributing; the maxi- mum number, four, is rarely found but three is fairly common. The central cell has only once been seen to germinate and the terminal hyaline cells apparently never do so. During germina- tion the setae gradually disintegrate. Germination was obtained as readily in a 2 per cent. solution of glucose as in water.

Spores placed on agar media readily produce an abundant mycelium. Different media were employed and gave growths of

A New Species of Monochaetia. 191

varying vigour. Luxuriant cultures were obtained on media prepared with extracts of prune, Scots pine, and potato and on the standard lemco-peptone medium. Media made with extracts of Douglas fir and ash only produced thin limited growths, consisting of delicate interwoven hyphae. Cultures made on bread soaked in the various extracts produced luxuriant cultures which never bore fructifications.

The mycelium is at first white but within a week assumes a coral-pink colour. The hypllac (fig. 5) are of variable thickness from 1-5-3-5p, hyaline in the earlier stages of growth, with granular protoplasm and no obvious inclusions or vacuoles. C,ross septa are numerous and the hyphae are freely branched; in many cases a septum is not present a t the point of insertion of a branch. The septa are commonly found at about a distance of 8 p apart but the elongating terminal cell may attain a length of 30p.

The assumption of the coral-pink colour is associated with two changes in the mycelium : (I) the development of stout thick-walled hyphae which contain aggregations of pink material in the cells (fig. 5, a) and ( 2 ) the appearance of strands of medium- sized hyphae with a parallel arrangement which take on a pink colour as a whole (fig. 5, b). The connection, if any, between these two phenomena, has not been determined.

Fructifications usually appear on the cultures after about ten days. The first indication of their development is the appearance of a minute dark mass slightly below the upper surface of the mycelium. A fructification always appears at the point of infection of the medium and is generally accompanied by a number of others scattered irregularly over the culture. The central fructification being usually the first to mature is, on dehiscence, a conspicuous feature (fig. 7). Development is very rapid and shortly after the dark masses have appeared a black shining drop is seen on the surface above each fructification indicating that dehiscence has commenced. This drop consists of a mass of extruded ~nucilage containing spores. The addition, or even the close proximity, of water causes a rapid change; the spores flow apart with great rapidity and only remain loosely held by the diffuse mass of thin mucilage. This will likewise occur, after a time, in an untouched culture. The fructifications produced on culture media agree generally in structure with those found on the leaves (fig. 6) ; the spores, however, are larger measuring 25-32 :,. 8 - ~ o p with stalks 8-z5p long and seta 10-50 p.

The extruded spores, if undisturbed, soon germinate. About three weeks after inoculation of the culture a bright pink tuft of mycelium is produced apically on the spore mass from the

192 Transactions British Mycological Society. germinating spores. This tuft extends to the base of the mass but does not spread to any extent over the surrounding mycelium.

The fungus under consideration clearly belongs to the genus Monochaetia, which is distinguished from Pestalozzia (of which it previously formed a part) by the presence of a single seta. A considerable number of species have been described in the former genus but few of these occur on conifers and we have been unable to find any of which the description agrees with the present fungus. In consequence we propose to make this a new species under the name Monochaetia Cry+tomeriae. There is no evidence to show that the species is parasitic, the fructi- fications only being found on the dead leaves lying on the ground. MONOCHAETIA CRYPTOMERIAE, n. sp.

Acervulis amphigenis, circularibus vel ovoideis, sparsis, sub- nigris, opacis haud nitentibus, laevibus, innato-erumpentibus, -75-1 mm. diam.; sporulis fusiformibus, utrinque acutiusculis, +septatis, vix constrictis, 22-30 x 7-5-10p, brunneis, loculis terminalibus hyalinis, apice setula, 20-32 x I p, hyalina, filiformi, curva dein rectiuscula terminatis; sporophoris filiformibus, - - hyalinis, 4-20 x 1-2 p.

Hab. in Scotia, Raith, Fife, in foliis dejectis Cryptomeriae japonicae.

DESCRIPTION OF PLATE VIII. Figs I, 2, 6 and 7 are from photographs; figs 3, 4 and 5 are from camera

lucida drawings. Fig. I. ~ ransverse section of the leaf of Cryptomeria japonica showing the

young fructification. x 190. Fig. 2. Similar section of a mature fructification. x 190. Fig. 3. Spores in different stages of development: a, proximal, e, distal ter-

minal cells; b, c, d, central cells; f, g, are probably early stages of develop- ment. x 610.

Fig. 4. Spores germinating in water; a t a, the germ-tube is bifurcating. x 610. Fig. 5. Mycelium from culture: a, stout hyphae containing aggregations of

pink material; b, strands of hyphae. x 610. Fig. 6. Section of fructification from culture. x 190. Fig. 7. Central portion of a culture showing fructifications which have

extruded their spores in masses of mucilage (natural size).

Trans. Brit. Myc. Socy. Vol. IX . PI. VIII .